A case of synovial sarcoma with abnormal expression of the human retinoblastoma susceptibility gene.

Abnormal or absent expression of the human retinoblastoma susceptibility (RB) gene has been implicated in the genesis of retinoblastoma. In addition to a 90% chance of developing retinoblastoma, patients inheriting a mutant RB gene have a high incidence of second nonocular malignancies, suggesting a role for this gene in other tumors as well. This report describes a patient without a previous history of retinoblastoma who developed metastatic synovial sarcoma. Analysis of RNA from this tumor revealed the presence of an abnormally long RB gene transcript in addition to an RB transcript of normal length. On the basis of findings in retinoblastoma, we propose that alteration of RB gene expression was significantly related to the formation of this patient's synovial sarcoma.